Fibers and nonwovens with increased surface roughness

Abstract

The present invention relates to fibers having an increased surface roughness. Further, the present invention relates to nonwovens, laminates and composites comprising such fibers. Additionally, the present invention relates to a process for producing such fibers, nonwovens, laminates and composites.

1 . Multicomponent fiber comprising an interior component and an exterior component, wherein said exterior component covers at least 50% of the surface of said fiber and comprises at least 70 wt % of a heterophasic propylene copolymer relative to the total weight of the exterior component, said heterophasic propylene copolymer comprising a propylene polymer matrix and a rubber. 
     
     
         2 . Multicomponent fiber according to  claim 1 , wherein the heterophasic propylene copolymer comprises a propylene polymer matrix and a rubber, said rubber comprising a first olefin, which is different from propylene, and a second olefin, which is different from the first olefin, said first olefin being present in an amount of from 2.0 wt % to 20.0 wt % relative to the total weight of the heterophasic propylene copolymer. 
     
     
         3 . Multicomponent fiber according to  claim 1 , wherein the heterophasic propylene copolymer is an ethylene-propylene rubber. 
     
     
         4 . Multicomponent fiber according to  claim 1 , wherein the rubber is present in an amount from 8.0 wt % to 24.0 wt % relative to the total weight of the heterophasic propylene copolymer. 
     
     
         5 . Nonwoven comprising the multicomponent fibers of to  claim 1 . 
     
     
         6 . Laminate or composite comprising the multicomponent fibers of  claim 1 . 
     
     
         7 . Process for the production of the multicomponent fiber of  claim 1 , comprising the steps of
 (a) providing a thermoplastic polymer to a first extruder,   (b) providing a polymer blend to a second extruder,   (c) melt-extruding the thermoplastic polymer of step (a) through a number of fine, usually circular, capillaries of a spinneret,   (d) melt-extruding the polymer blend of step (h) through a number of fine openings surrounding said capillaries of step (c), and   (e) combining the extrudates of steps (c) and (d) to form single fibers of an intermediate diameter, such that the extrudate of step (d) forms an exterior component covering at least 50% of the surface of the fiber produced by combining the extrudates,   wherein the polymer blend of step (b) comprises at least 70 wt % of a heterophasic propylene, said heterophasic propylene copolymer comprising a propylene polymer matrix and a rubber.   
     
     
         8 . Process according to  claim 7 , wherein the heterophasic propylene copolymer comprises a propylene polymer matrix and a rubber, said rubber comprising a first olefin, which is different from propylene, and a second olefin, which is different from the first olefin, said first olefin being present in an amount of from 2.0 wt % to 20.0 wt % relative to the total weight of the heterophasic propylene copolymer. 
     
     
         9 . Process according to  claim 7 , wherein the heterophasic propylene copolymer is an ethylene-propylene rubber. 
     
     
         10 . Process according to  claim 7 , wherein the rubber is present in an amount from 8.0 wt % to 24.0 wt % relative to the total weight of the heterophasic propylene copolymer. 
     
     
         11 . Process according to  claim 7 , wherein the process further comprises the step of
 (f) rapidly reducing the intermediate diameter of the fiber extruded in step (e) to a final diameter.   
     
     
         12 . Process according to  claim 7 , wherein the process further comprises the steps of
 (g) collecting the fibers obtained in step (e) or step (f) on a support, and   (h) subsequently bonding the collected fibers to form a bonded nonwoven.   
     
     
         13 . Process according to  claim 7 , wherein the bonded nonwoven is a spunbond nonwoven or a spunlaced nonwoven.